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slirp: Add domain-search option to slirp's DHCP server

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This patch will allow the user to include the domain-search option in
replies from the built-in DHCP server. The domain suffixes can be
specified by adding dnssearch= entries to the "-net user" parameter.

[Jan: tiny style adjustments]

Signed-off-by: Klaus Stengel <Klaus.Stengel@asamnet.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
This commit is contained in:
Klaus Stengel 2012-10-27 19:53:39 +02:00 committed by Jan Kiszka
parent 1a89b60885
commit 63d2960bc4
9 changed files with 392 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
net/slirp.c
View File

@ -136,7 +136,7 @@ static int net_slirp_init(NetClientState *peer, const char *model,
const char *vhostname, const char *tftp_export,
const char *bootfile, const char *vdhcp_start,
const char *vnameserver, const char *smb_export,
const char *vsmbserver)
const char *vsmbserver, const char **dnssearch)
{
/* default settings according to historic slirp */
struct in_addr net = { .s_addr = htonl(0x0a000200) }; /* 10.0.2.0 */
@ -242,7 +242,7 @@ static int net_slirp_init(NetClientState *peer, const char *model,
s = DO_UPCAST(SlirpState, nc, nc);
s->slirp = slirp_init(restricted, net, mask, host, vhostname,
tftp_export, bootfile, dhcp, dns, s);
tftp_export, bootfile, dhcp, dns, dnssearch, s);
QTAILQ_INSERT_TAIL(&slirp_stacks, s, entry);
for (config = slirp_configs; config; config = config->next) {
@ -699,6 +699,31 @@ net_init_slirp_configs(const StringList *fwd, int flags)
}
}
static const char **slirp_dnssearch(const StringList *dnsname)
{
const StringList *c = dnsname;
size_t i = 0, num_opts = 0;
const char **ret;
while (c) {
num_opts++;
c = c->next;
}
if (num_opts == 0) {
return NULL;
}
ret = g_malloc((num_opts + 1) * sizeof(*ret));
c = dnsname;
while (c) {
ret[i++] = c->value->str;
c = c->next;
}
ret[i] = NULL;
return ret;
}
int net_init_slirp(const NetClientOptions *opts, const char *name,
NetClientState *peer)
{
@ -706,6 +731,7 @@ int net_init_slirp(const NetClientOptions *opts, const char *name,
char *vnet;
int ret;
const NetdevUserOptions *user;
const char **dnssearch;
assert(opts->kind == NET_CLIENT_OPTIONS_KIND_USER);
user = opts->user;
@ -714,6 +740,8 @@ int net_init_slirp(const NetClientOptions *opts, const char *name,
user->has_ip ? g_strdup_printf("%s/24", user->ip) :
NULL;
dnssearch = slirp_dnssearch(user->dnssearch);
/* all optional fields are initialized to "all bits zero" */
net_init_slirp_configs(user->hostfwd, SLIRP_CFG_HOSTFWD);
@ -722,7 +750,7 @@ int net_init_slirp(const NetClientOptions *opts, const char *name,
ret = net_slirp_init(peer, "user", name, user->q_restrict, vnet,
user->host, user->hostname, user->tftp,
user->bootfile, user->dhcpstart, user->dns, user->smb,
user->smbserver);
user->smbserver, dnssearch);
while (slirp_configs) {
config = slirp_configs;
@ -731,6 +759,7 @@ int net_init_slirp(const NetClientOptions *opts, const char *name,
}
g_free(vnet);
g_free(dnssearch);
return ret;
}

4
qapi-schema.json
View File

@ -2404,6 +2404,9 @@
#
# @dns: #optional guest-visible address of the virtual nameserver
#
# @dnssearch: #optional list of DNS suffixes to search, passed as DHCP option
# to the guest
#
# @smb: #optional root directory of the built-in SMB server
#
# @smbserver: #optional IP address of the built-in SMB server
@ -2426,6 +2429,7 @@
'*bootfile': 'str',
'*dhcpstart': 'str',
'*dns': 'str',
'*dnssearch': ['String'],
'*smb': 'str',
'*smbserver': 'str',
'*hostfwd': ['String'],

18
qemu-options.hx
View File

@ -1318,8 +1318,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net,
" create a new Network Interface Card and connect it to VLAN 'n'\n"
#ifdef CONFIG_SLIRP
"-net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=on|off]\n"
" [,hostname=host][,dhcpstart=addr][,dns=addr][,tftp=dir][,bootfile=f]\n"
" [,hostfwd=rule][,guestfwd=rule]"
" [,hostname=host][,dhcpstart=addr][,dns=addr][,dnssearch=domain][,tftp=dir]\n"
" [,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
#ifndef _WIN32
"[,smb=dir[,smbserver=addr]]\n"
#endif
@ -1428,7 +1428,7 @@ able to contact the host and no guest IP packets will be routed over the host
to the outside. This option does not affect any explicitly set forwarding rules.
@item hostname=@var{name}
Specifies the client hostname reported by the builtin DHCP server.
Specifies the client hostname reported by the built-in DHCP server.
@item dhcpstart=@var{addr}
Specify the first of the 16 IPs the built-in DHCP server can assign. Default
@ -1439,6 +1439,18 @@ Specify the guest-visible address of the virtual nameserver. The address must
be different from the host address. Default is the 3rd IP in the guest network,
i.e. x.x.x.3.
@item dnssearch=@var{domain}
Provides an entry for the domain-search list sent by the built-in
DHCP server. More than one domain suffix can be transmitted by specifying
this option multiple times. If supported, this will cause the guest to
automatically try to append the given domain suffix(es) in case a domain name
can not be resolved.
Example:
@example
qemu -net user,dnssearch=mgmt.example.org,dnssearch=example.org [...]
@end example
@item tftp=@var{dir}
When using the user mode network stack, activate a built-in TFTP
server. The files in @var{dir} will be exposed as the root of a TFTP server.

2
slirp/Makefile.objs
View File

@ -1,3 +1,3 @@
common-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o
common-obj-y = cksum.o if.o ip_icmp.o ip_input.o ip_output.o dnssearch.o
common-obj-y += slirp.o mbuf.o misc.o sbuf.o socket.o tcp_input.o tcp_output.o
common-obj-y += tcp_subr.o tcp_timer.o udp.o bootp.o tftp.o arp_table.o

12
slirp/bootp.c
View File

@ -287,6 +287,18 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
memcpy(q, slirp->client_hostname, val);
q += val;
}
if (slirp->vdnssearch) {
size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
val = slirp->vdnssearch_len;
if (val + 1 > spaceleft) {
g_warning("DHCP packet size exceeded, "
"omitting domain-search option.");
} else {
memcpy(q, slirp->vdnssearch, val);
q += val;
}
}
} else {
static const char nak_msg[] = "requested address not available";

314
slirp/dnssearch.c Normal file
View File

@ -0,0 +1,314 @@
/*
* Domain search option for DHCP (RFC 3397)
*
* Copyright (c) 2012 Klaus Stengel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <glib.h>
#include "slirp.h"
static const uint8_t RFC3397_OPT_DOMAIN_SEARCH = 119;
static const uint8_t MAX_OPT_LEN = 255;
static const uint8_t OPT_HEADER_LEN = 2;
static const uint8_t REFERENCE_LEN = 2;
struct compact_domain;
typedef struct compact_domain {
struct compact_domain *self;
struct compact_domain *refdom;
uint8_t *labels;
size_t len;
size_t common_octets;
} CompactDomain;
static size_t
domain_suffix_diffoff(const CompactDomain *a, const CompactDomain *b)
{
size_t la = a->len, lb = b->len;
uint8_t *da = a->labels + la, *db = b->labels + lb;
size_t i, lm = (la < lb) ? la : lb;
for (i = 0; i < lm; i++) {
da--; db--;
if (*da != *db) {
break;
}
}
return i;
}
static int domain_suffix_ord(const void *cva, const void *cvb)
{
const CompactDomain *a = cva, *b = cvb;
size_t la = a->len, lb = b->len;
size_t doff = domain_suffix_diffoff(a, b);
uint8_t ca = a->labels[la - doff];
uint8_t cb = b->labels[lb - doff];
if (ca < cb) {
return -1;
}
if (ca > cb) {
return 1;
}
if (la < lb) {
return -1;
}
if (la > lb) {
return 1;
}
return 0;
}
static size_t domain_common_label(CompactDomain *a, CompactDomain *b)
{
size_t res, doff = domain_suffix_diffoff(a, b);
uint8_t *first_eq_pos = a->labels + (a->len - doff);
uint8_t *label = a->labels;
while (*label && label < first_eq_pos) {
label += *label + 1;
}
res = a->len - (label - a->labels);
/* only report if it can help to reduce the packet size */
return (res > REFERENCE_LEN) ? res : 0;
}
static void domain_fixup_order(CompactDomain *cd, size_t n)
{
size_t i;
for (i = 0; i < n; i++) {
CompactDomain *cur = cd + i, *next = cd[i].self;
while (!cur->common_octets) {
CompactDomain *tmp = next->self; /* backup target value */
next->self = cur;
cur->common_octets++;
cur = next;
next = tmp;
}
}
}
static void domain_mklabels(CompactDomain *cd, const char *input)
{
uint8_t *len_marker = cd->labels;
uint8_t *output = len_marker; /* pre-incremented */
const char *in = input;
char cur_chr;
size_t len = 0;
if (cd->len == 0) {
goto fail;
}
cd->len++;
do {
cur_chr = *in++;
if (cur_chr == '.' || cur_chr == '\0') {
len = output - len_marker;
if ((len == 0 && cur_chr == '.') || len >= 64) {
goto fail;
}
*len_marker = len;
output++;
len_marker = output;
} else {
output++;
*output = cur_chr;
}
} while (cur_chr != '\0');
/* ensure proper zero-termination */
if (len != 0) {
*len_marker = 0;
cd->len++;
}
return;
fail:
g_warning("failed to parse domain name '%s'\n", input);
cd->len = 0;
}
static void
domain_mkxrefs(CompactDomain *doms, CompactDomain *last, size_t depth)
{
CompactDomain *i = doms, *target = doms;
do {
if (i->labels < target->labels) {
target = i;
}
} while (i++ != last);
for (i = doms; i != last; i++) {
CompactDomain *group_last;
size_t next_depth;
if (i->common_octets == depth) {
continue;
}
next_depth = -1;
for (group_last = i; group_last != last; group_last++) {
size_t co = group_last->common_octets;
if (co <= depth) {
break;
}
if (co < next_depth) {
next_depth = co;
}
}
domain_mkxrefs(i, group_last, next_depth);
i = group_last;
if (i == last) {
break;
}
}
if (depth == 0) {
return;
}
i = doms;
do {
if (i != target && i->refdom == NULL) {
i->refdom = target;
i->common_octets = depth;
}
} while (i++ != last);
}
static size_t domain_compactify(CompactDomain *domains, size_t n)
{
uint8_t *start = domains->self->labels, *outptr = start;
size_t i;
for (i = 0; i < n; i++) {
CompactDomain *cd = domains[i].self;
CompactDomain *rd = cd->refdom;
if (rd != NULL) {
size_t moff = (rd->labels - start)
+ (rd->len - cd->common_octets);
if (moff < 0x3FFFu) {
cd->len -= cd->common_octets - 2;
cd->labels[cd->len - 1] = moff & 0xFFu;
cd->labels[cd->len - 2] = 0xC0u | (moff >> 8);
}
}
if (cd->labels != outptr) {
memmove(outptr, cd->labels, cd->len);
cd->labels = outptr;
}
outptr += cd->len;
}
return outptr - start;
}
int translate_dnssearch(Slirp *s, const char **names)
{
size_t blocks, bsrc_start, bsrc_end, bdst_start;
size_t i, num_domains, memreq = 0;
uint8_t *result = NULL, *outptr;
CompactDomain *domains = NULL;
const char **nameptr = names;
while (*nameptr != NULL) {
nameptr++;
}
num_domains = nameptr - names;
if (num_domains == 0) {
return -2;
}
domains = g_malloc(num_domains * sizeof(*domains));
for (i = 0; i < num_domains; i++) {
size_t nlen = strlen(names[i]);
memreq += nlen + 2; /* 1 zero octet + 1 label length octet */
domains[i].self = domains + i;
domains[i].len = nlen;
domains[i].common_octets = 0;
domains[i].refdom = NULL;
}
/* reserve extra 2 header bytes for each 255 bytes of output */
memreq += ((memreq + MAX_OPT_LEN - 1) / MAX_OPT_LEN) * OPT_HEADER_LEN;
result = g_malloc(memreq * sizeof(*result));
outptr = result;
for (i = 0; i < num_domains; i++) {
domains[i].labels = outptr;
domain_mklabels(domains + i, names[i]);
outptr += domains[i].len;
}
if (outptr == result) {
g_free(domains);
g_free(result);
return -1;
}
qsort(domains, num_domains, sizeof(*domains), domain_suffix_ord);
domain_fixup_order(domains, num_domains);
for (i = 1; i < num_domains; i++) {
size_t cl = domain_common_label(domains + i - 1, domains + i);
domains[i - 1].common_octets = cl;
}
domain_mkxrefs(domains, domains + num_domains - 1, 0);
memreq = domain_compactify(domains, num_domains);
blocks = (memreq + MAX_OPT_LEN - 1) / MAX_OPT_LEN;
bsrc_end = memreq;
bsrc_start = (blocks - 1) * MAX_OPT_LEN;
bdst_start = bsrc_start + blocks * OPT_HEADER_LEN;
memreq += blocks * OPT_HEADER_LEN;
while (blocks--) {
size_t len = bsrc_end - bsrc_start;
memmove(result + bdst_start, result + bsrc_start, len);
result[bdst_start - 2] = RFC3397_OPT_DOMAIN_SEARCH;
result[bdst_start - 1] = len;
bsrc_end = bsrc_start;
bsrc_start -= MAX_OPT_LEN;
bdst_start -= MAX_OPT_LEN + OPT_HEADER_LEN;
}
g_free(domains);
s->vdnssearch = result;
s->vdnssearch_len = memreq;
return 0;
}

3
slirp/libslirp.h
View File

@ -12,7 +12,8 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
struct in_addr vnetmask, struct in_addr vhost,
const char *vhostname, const char *tftp_path,
const char *bootfile, struct in_addr vdhcp_start,
struct in_addr vnameserver, void *opaque);
struct in_addr vnameserver, const char **vdnssearch,
void *opaque);
void slirp_cleanup(Slirp *slirp);
void slirp_update_timeout(uint32_t *timeout);

8
slirp/slirp.c
View File

@ -203,7 +203,8 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
struct in_addr vnetmask, struct in_addr vhost,
const char *vhostname, const char *tftp_path,
const char *bootfile, struct in_addr vdhcp_start,
struct in_addr vnameserver, void *opaque)
struct in_addr vnameserver, const char **vdnssearch,
void *opaque)
{
Slirp *slirp = g_malloc0(sizeof(Slirp));
@ -233,6 +234,10 @@ Slirp *slirp_init(int restricted, struct in_addr vnetwork,
slirp->vdhcp_startaddr = vdhcp_start;
slirp->vnameserver_addr = vnameserver;
if (vdnssearch) {
translate_dnssearch(slirp, vdnssearch);
}
slirp->opaque = opaque;
register_savevm(NULL, "slirp", 0, 3,
@ -252,6 +257,7 @@ void slirp_cleanup(Slirp *slirp)
ip_cleanup(slirp);
m_cleanup(slirp);
g_free(slirp->vdnssearch);
g_free(slirp->tftp_prefix);
g_free(slirp->bootp_filename);
g_free(slirp);

5
slirp/slirp.h
View File

@ -235,6 +235,8 @@ struct Slirp {
/* bootp/dhcp states */
BOOTPClient bootp_clients[NB_BOOTP_CLIENTS];
char *bootp_filename;
size_t vdnssearch_len;
uint8_t *vdnssearch;
/* tcp states */
struct socket tcb;
@ -294,6 +296,9 @@ void lprint(const char *, ...) GCC_FMT_ATTR(1, 2);
#define SO_OPTIONS DO_KEEPALIVE
#define TCP_MAXIDLE (TCPTV_KEEPCNT * TCPTV_KEEPINTVL)
/* dnssearch.c */
int translate_dnssearch(Slirp *s, const char ** names);
/* cksum.c */
int cksum(struct mbuf *m, int len);